Human microbial alterations are associated with environmental stress, nutritional, genetic and triggering de-novo variations. Nevertheless, human gut microbiome at extreme altitude (>5800 m) remains unexplored. We aimed to demonstrate the microbial predominance in individuals with same ethnicity and dietary pattern at extreme altitude with unique challenges like cold, hypoxia, radiation etc. Different analysis pipelines were used for fecal whole genome sequencing at 210m, 3500m, 4420m and 5805m, and 16s rRNA V3-V4 regions amplification sequencing of 19 individuals belonging to the same ethnicity and dietary pattern, for presence of taxonomy & functional potential and confirming the prediction upto the strain level within the same cohort. Principal component analysis, revealed distinct microbiome changes at different altitudes, with varied and higher Bacteroides and Prevotella ratio. There was predominance of genus Prevotella at altitudes 4420m & 5805m than at 210m & 3500m. Appearance of species Prevotella copri strain 61740 was increasing significantly at extreme altitudes, whereas co-occurrence of other bacterial strains had different pattern than Prevotella. The extensive strain level analysis indicated alteration in the metabolic pathways. This study under stressful and hypoxic environment of extreme altitudes, associated microbial variation with altered metabolic pathways, reveals influence of extreme environment on human gut microbiota with predominance of Prevotella.